1. Field of the Invention
The invention relates to a anti-piracy recording disk and a process for recording and reading such a disk. The invention is applicable in particular in the field of optical disks and magneto-optical disks.
2. Disussion of the Background
Compact disks of the CD-ROM type and DVDs (Digital Video Disks) are used to disseminate all kinds of information (data, programs). Traditionally, these disks were not susceptible to data piracy since their capacity was greater than that of most storage means on the market. With the appearance on the one hand of high-capacity hard disks, and on the other hand of cheap CD-ROM etchers, this situation is completely altered. The duplicating of data is now within the scope of semi-professionals or even amateurs.
In the various recording media, from the hard disk to the optical disk and to the magnetic tape, the information is grouped into elements generally called blocks. A table of contents allocating the blocks to the various files is recorded somewhere on the same medium. For example, the blocks of a Digital Audio (DA) CD are allocated to each of the recorded pieces of music via this table of contents. Likewise, the blocks of a CD-ROM are each allocated to relevant computer files. Each block number contains a data set, the goal being for the set of data retrieved to perfectly reproduce those which were recorded, the same ones at each access. Error correcting codes reduce the inevitable error rate to an acceptable value for the relevant application.
In a conventional disk, the information is written sequentially on a spiral. The various addresses are arranged in a numerical order. The reading of the information is therefore carried out sequentially. The invention relates to a recording disk in which reading cannot be carried out in a sequential manner.
The invention provides a solution making it possible to detect a recording which has been copied fraudulently and even to render this recording unusable.
The invention therefore relates to an information recording disk comprising a main recording track recorded in a general manner in the form of a spiral comprising a plurality of segments of almost concentric turns, characterized in that the said main track comprises one or more interruptions and/or changes of turn and in that the addresses of the blocks and/or sectors are not arranged sequentially on the track.